peterv Posted June 26, 2013 Share #1 Posted June 26, 2013 Advertisement (gone after registration) Hi, I've been playing around with DNG Validation in LR 5 and when I try to let LR check my DNG's I get the message the files are 'not validated'. This does not mean they're 'invalid', just that LR is unable to 'validate'. It seems this option does not function with DNG's from Leica because the cameras don't write the hash that's necessary for reference into the file. Here's what Victoria Bampton writes about this subject: Not Validated means there’s no hash to compare against (for example, some DNG files created by cameras don’t embed a hash) or the original files are missing. Leica's marketing tells us they use DNG because it's universal and future proof. That's all fine and dandy, but than they should allow our cameras to write the necessary hashtag into the files. Our Leica DNG files will be more future proof when we can check for bit rot. Perhaps I completely misunderstood, and there's something else going on? Sandy? Does anyone else know more about how this works? Thanks! Link to post Share on other sites More sharing options...
Advertisement Posted June 26, 2013 Posted June 26, 2013 Hi peterv, Take a look here LR 5 (Leica) DNG Validation. I'm sure you'll find what you were looking for!
ho_co Posted June 27, 2013 Share #2 Posted June 27, 2013 Peter-- What camera are you using? Link to post Share on other sites More sharing options...
peterv Posted June 27, 2013 Author Share #3 Posted June 27, 2013 Howard, these days I shoot with the S2, but the above also applies to my old M8 DNG's. Link to post Share on other sites More sharing options...
sandymc Posted June 27, 2013 Share #4 Posted June 27, 2013 What Victoria is talking about is the "RawImageDigest" tag - it's an MD5 hash of the raw image data. If LR detects that the digest is different to the MD5 hash of the current image data, it will throw up a validation failure. However, (a) the field is optional and ( was only included from V1.2 of the DNG spec. As all of Leica's cameras that I can think of stick with the DNG 1.1 spec, presumably to maximize compatibility, they don't include the field. Hence the message. The LR developers probably should have chosen different wording for the message; it should not really be saying "not validated" - "not applicable" or something like that would be more appropriate for DNG 1.1 files. Something to be aware of with DNG validation is that validation is only for the actual raw data. Changes anywhere else in the image file, e.g., to any of the metadata, etc would not be detected. Sandy Link to post Share on other sites More sharing options...
A Sfeir Posted June 27, 2013 Share #5 Posted June 27, 2013 I just ran a validation check on all photos (M8, 9 and M) in my library. No problem Link to post Share on other sites More sharing options...
sandymc Posted June 27, 2013 Share #6 Posted June 27, 2013 I just ran a validation check on all photos (M8, 9 and M) in my library. No problem Depending on how you have LR configured, LR will convert 1.1 DNGs to the newer spec, and add the digest tags. Sandy Link to post Share on other sites More sharing options...
peterv Posted June 28, 2013 Author Share #7 Posted June 28, 2013 Advertisement (gone after registration) Many thanks Sandy, do you think Leica will change to V1.2 of the DNG spec? Regarding the compatibility of V1.1, is their still benefit in using it? Depending on how you have LR configured, LR will convert 1.1 DNGs to the newer spec, and add the digest tags. I presume this refers to the 'import as DNG' option in LR or using the DNG Converter. Would you recommend doing this with Leica DNG's for more compatibility with Adobe Software? Would there be a downside to such a workflow, apart from the extra work? Link to post Share on other sites More sharing options...
sandymc Posted June 28, 2013 Share #8 Posted June 28, 2013 Many thanks Sandy, do you think Leica will change to V1.2 of the DNG spec? Regarding the compatibility of V1.1, is their still benefit in using it? I presume this refers to the 'import as DNG' option in LR or using the DNG Converter. Would you recommend doing this with Leica DNG's for more compatibility with Adobe Software? Would there be a downside to such a workflow, apart from the extra work? There really isn't benefit to 1.2 for the existing cameras, so I'd be very surprised is Leica changed. You may possibly see future cameras with DNG 1.3; Leica could, if they wanted to, do away with the current vignetting correction on raw data, and do so via DNG 1.3's system of "op codes". However, that is a huge compatibility issue; so far as I am aware only LR and PhotoShop fully implement op codes. Personally, I always try to keep my DNGs in original form, in case I want to use non-Adobe software on them - there is no guarantee that after conversion another raw developer would be able to read them. Sandy Link to post Share on other sites More sharing options...
peterv Posted June 28, 2013 Author Share #9 Posted June 28, 2013 Sandy, thanks for taking the time to answer. Cheers, Peter Link to post Share on other sites More sharing options...
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